Electron discharge devices



Aug- 11, 1959 A. K. WING, JR., ETL

ELECTRON DISCHARGE DEVICES Filed May 5, 1954 2+ United States Patent C ELECTRON DISCHARGE DEVICES Arthur K. Wing, Jr., Nutley, and Herbert W. Cole,

- Cedar Grove, N J., assignors to International Telephone and Telegraph Corporation, Nutley, NJ., a `corporation of Maryland Application May 3, 1954, Serial No. 427,267

9 Claims. (Cl. S15-3.5)

This invention relates to electron discharge devices and more particularly to improved means for coupling energy toelements thereof.

In the fabrication of electron discharge devices, numerous problems are encountered in both the stem portion and the radio frequency portion of microwave type electron discharge devices. The stem portion problem is of course not limited to microwave type discharge devices, to the contrary, it is encountered in all types of devices having a stem portion where connections to the electrodes thereof, from an external source, are accomplished by means of pins fused into a glass or ceramic base. The problem encountered in fabricating the ceramic stem portion is the precision bore required in .the ceramic base and the difficulty of coating the surface of the bore to accomplish the sweating of the pins into this bore. In the fabrication of the glass stem portion difculty is encountered in the maintenance of accurate positioning of the leads brought therethrough. The improved coupling means of this invention will speed up and increase the ease of fabricating electron discharge device stern presses and appreciably reduce the cost of such stem presses.

The problem encountered in the radio frequency portion of microwave type electron discharge devices is somewhat more complex than the stem portion problem, but is solved as simply land easily byv employing the coupling means of this invention. In microwave type electron discharge devices including traveling wave tubes,`

klystrons and magnetrons, it is' necessary to couple radio frequency into or out of an interaction region. To accomplish the desired energy coupling in an eiicient manner, the impedance of the interaction section must be matched by the input or output transmission line as the case may be. In the past the transmission line, employed as part of the impedance matching section, has been disposed internally of, or las a part of, the vacuum closure.' This type of structure requires the inclusion of glass 'beads within the transmission line to provide the necessaryy vacuum seal. This work is tedious and the glass beads .tend to crack causing a leaky tube. Not only is the fabrication of such elements time consuming and expensive, but if the tube becomes defective during processing due to some vacuum tube fault, non-ernissive cathode or similar di'iculty, the transmission line and the matching section were Valso lost with the rejected tube, thereby lconsiderably increasing the cost of the good tubes produced. The coupling means of this invention enables the major portion of the impedance matching section to be external to the vacuum envelope which provides ease in nal adjustment when necessary and is a large cost reducing factor. The cost reduction is brought about structurally as indicated above and in addition by a reduction of `time in the outgas process o f a given discharge device. Reduction in time vfor outgassing a discharge device is accomplished 'by decreasing the metal components vwithin the vacuum enclosurer ICC ment of ceramic materials in the fabrication of the tubes..

Therefore, it is an object of this invention to provide an improved means for coupling energy to elements of an electron discharge device resulting in a relatively inexpensive structure having operating characteristics equivalent to or exceeding the operating characteristics of previous coupling arrangements for electron discharge devices.

Another object of this invention is to provide an improved radio frequency coupling means contiguous Ito the interaction section of a microwave type electron discharge device including an impedance match section disposed primarily externally of the vacuum closure of an electron discharge device.

Still another object of this invention is to provide an improved -all ceramic stem press construction enabling conduction of D.C. potential to the electrodes of electron discharge devices.

A feature of this invention is the provision of a ceramic member disposed crosswise an electron discharge device envelope, a conductive line carried on a surface of the ceramic member extending from the vacuum side to the atmospheric side of'the envelope, and a sealing means to unite the surface of the ceramic member and the conductive line thereon with the envelope.

Another feature of this invention is a radio frequency coupling means for substantial reflectionless transition of radio frequency energy between a low impedance transmission line to a high impedance transmission line including a flat conductive strip spaced from a planar conducting surface by means of dielectric material, a first portion thereof providing an impedance matching section, a second portion thereof contiguous a transmission line terminal connection, and a third portion thereof extending through a vacutun closure into the interaction region of a microwave type electron discharge device, and means sealing the dielectric material and the conductive strip thereon to the vacuum closure as an integral portion thereof.

A further feature of this invention is the provision of a ceramic disc carrying on a surface thereof a plurality of conducting strips and means to seal said surface inp cluding said strips to the tubular end portion of a vacuum i cluded withinan electron discharge device.

The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction'with the accompanying drawings, in which:

Fig. 1 is a fragmentary 'view in longitudinal section of a traveling wave electron discharge device incorporating an improved radio frequency coupling means at the ends of the interaction region and an improved stem press portion in accordance with the principles of thix invention;

Fig. 2 is a fragmentary view in elevation partially in section as viewed along line 2-2 of Fig. l;

Fig. 3 is a fragmentary view in longitudinal section showing another form of radio frequency coupling means;`

`and

y parts of a traveling wave electron discharge'device are" shown together with an illustrationof an embodimentof PatentedA Aug. 11, A1959I collector 2. The electron `gunl unit is either' separated fromi or made contiguous to` anV alignment or partition plate 3 whichV is positioned crosswise envelope 4-which is usually composed of ceramic' material. Carried ontheouter surfaceA of envelope 4 is either a permanent magnet or magnetic coil 5 which serves `to' produce a magnetic field axially of envelope 4. At the rear of the envelope is a` second alignment:- or partition plate 6, both of the plates 3 andV 6 being of magnetic material having good' conductivity. Interposed between' these two plates 3 and 6 is. an interaction section 7 including a helical transmission line 8 supported by dielectric rods 9 or by a dielectric tube, Whichever is desired. Any suitable dielectric, such as glass or quartzv may be employed; The rods or tubing, as the case may be, are supported on the plates 3 and 6 in openings 10 and 11, respectively. The helical line 8 is connected between the input and output R-F terminal connections 12 and 13 by means of radio frequency coupling means 14 and 15, respectively.

The coupling means 14, for example, comprises aparallel line or wave-guide arrangement which includes plate 3' as one of the conductors and a flat conducting strip' 16 as the other conductor. Strip 16 is separatedl from the parallel planar surface of plate 3 by dielectric material 17 having an annular wafer configuration. The dielectric material may comprise any dielectric material suitable for use within a vacuum enclosure, such as glass, quartz or ceramic. Strip 16 is preferably supported on the solid dielectric material. The at strip 16 has a dimension of approximately one quarter wavelength long or an odd` multiple thereof at the operating frequency of the device. For further disclosure of this general type of transmission line, reference may be made to the copending applications of D. D. Grieg-H. F. Engelmann, Serial' No. 227,896, tiled May 23, 1951, now abandoned, and Serial No. 234,503, tiled lune 30, 1951, now Patent No. 2,721,- 312, and M. Arditi-P. Parzen, Serial No. 286,764, filed May 8, 1952, now Patent No. 2,774,046. The strip 16 should be applied to material 17 to form a vacuum tight bond and shaped according to printed circuit technique. This type of strip conductor, spaced a small fraction of a quarter wavelength from the parallel planar surface of the conducting plate 3, provides a form of parallel waveguide for propagation of electromagnetic waves from the coaxial connection 12 in a mode closely simulatingV the TEM mode. The strip 16 is preferably of a width suicient to provide satisfactory coupling to the coaxial transmission line and includes a transition piece 18 in coupled relation with the vacuum portion of strip 16 at a high voltage point thereon. Piece 18` is tapered as indicated in Fig. 2 to provide a gradual transition from lthe strip width down to the conductor size forming the helical transmission line. The space dimension h between strip 16 and the planar conducting surface of plate 3 to cooperate in` matching the impedance of connection 12 to the impedance of line 8 may be obtained from the expression portion 21 which provides a short circuit between the.

planar conducting surface of plate 3 and strip 16. Flange 21 locates a voltage null or zero impedance point and is disposed approximately a quarter wavelength from the.

4 point of coupling between strip 16 and the helix 8. The impedance at this coupling point would be equivalent to the high impedance of the helix and the impedance along the matching section would vary in a given manner between this high impedance point and the zero impedance point. At a point along section 14, the low impedance line 12 is coupled at an appropriate point along section 14, consistent with the low impedance of line 12, by means of bridge member 20 for coupling center conductor 19 to strip 16. Such a matching section provides a lowl voltage standing wave ratio and accomplishes a broad frequency match between the characteristic impedances of the two transmission lines in question. The coupling means 1'4 extends from` the atmospheric: surroundings of envelope 4 into the vacuum portion of envelope 4. The radio frequency energy is coupled from strip 16 to the helical transmission line 8 through means of transition piece 18 which reduces the conductor in size from the width. of strip 16- to approximately the diameter of the wire forming helix 8.

The radio frequency coupling means 15 is identical to. the form shown at 14, the propagation therealong, however, being` in the reverse direction over the coupling, means. Envelope 4 is placed in contactwith conducting, strip 16 and sealed to the dielectric material 17 and strip4 16 to insure a vacuumtight bond. A known ceramic-tometal. sealing technique may be employed to provide` ther desired vacuum tight bond between member 17 and strip- 16. This ceramic-to-metal sealing technique may include the tungsten-oxide method or molybdenum-iron method as. the situation dictates. The member 17 and strip 16 car ried thereby is sealed to envelope 4 by employing a glazing, material which wets both dielectric members and strip 16 and then' fused to give a vacuum tight seal.

While the embodiment of this invention illustrated. in; Figs. 1 and 2 shows the planar surface of the coupling, means to be an alignment plate of the electron discharge, device, it should be understood that a plate or other planar surface separate from any alignment plate may be em-l ployed. The embodiment of Fig. 3 illustrates a coupling means 22 which may be incorporated in an electrony dis.- charge device having an all ceramic vacuum envelope. Such a coupling means provides a conducting strip 23` applied to dielectric material 24 having a wafer configura-Y tion according to printed circuit techniques as outlined' hereinabove in connection with conducting stripy 16 ofY coupling means 14. Conducting strip 23 functions as the planar conducting surface for the conducting stripl 25 which couples radio frequency energy from `terminal 12a to the helical propagating structure whereby an impedance transition is accomplished between the low impedance terminal 12a and the high impedance helical line 8a. Coupling means 22 provides an impedance matching section. substantially in the same manner as provided in coupling` means 14 as indicated at 26 with the desired matching sec-y tion being wholly external to the vacuum region of the. electron discharge device. To couple the radio frequency energy into the vacuum region for connection to helical. line 8a, the ceramic envelope 27 is sealed to both surfaces of wafer 24 and the conducting strips 23 and 25 by employing a glaze sealing technique as outlined hereinabove in connection with coupling means 14.

The coupling region of coupling means 22 dilers from the coupling region of coupling means 14 in that the dielectric material 24 has an aperture therein only large` enough to receive the center conductor 19a of terminal 12a. Strip 25 completely covers the aperture 28 in material 24. Conductor 19a is then either soldered or welded,. or otherwise secured, to the surface of strip 25 to makey a. direct butt contact therewith. It is to be understood that this butt type contact can likewise beV employed in cou.- pling means 14 in place of the bridge type arrangement illustrated in Fig. 1.

Referring to Figs. 1 and 4, we have illustrated thereinr au embodiment of ythe novel stem press arrangement ofi g the' present invention. The stem press 29 of the electron discharge device of Fig. 1 includes a ceramic base member 30 having a disc conguration. It is proposed to place a conducting strip 31 at appropriately spaced positions on disc 30, with each of the strips extending into what will be the vacuum portion of the stem press along one face of disc 30 and to provide a continuous path over the periphery of disc 30. These conducting strips may be' applied to disc 30 by again employing a known ceramicto-metal sealing technique to provide the desired vacuum tight bond between strips 31 and disc 30. Each of the conducting strips 31 are provided with post connections 32 which extend from the stem press portion into the electron discharge device to couple operating potential to the electrodes of the electron discharge device, for example, the electron gun electrodes of the device in Fig. l. 'Ihe vacuum envelope 33 of the stem press portion, a tubular end portion longitudinal extension of envelope 4, is sealed to the surface of ceramic disc 30 facing the end of envelope 33 and metal strips 31 carried thereon by wetting the end of envelope 33 and the disc 30 including strips 31 with a glazing material and fusing these members together to provide a vacuum tight bond.

The desired potentials for the operation of the elec-i trodes within the electron discharge device can be connected to the strips 31 at the flanged portion 34 by means of leads soldered thereto or "by means of the spring fingers 3S illustrated in Fig. 1.

While the embodiment disclosed herein illustrates only three D.C. connections, it is obvious that the number of connections may be increased and appropriately positioned on the face of disc 30 to accommodate the connection of D.C. potentials to any desired number of electrode elements. The utilization of connecting strips 31 in coupling potential to the various electrodes has been found to increase the power handling capacity of the stem press over a stem press employing round wires of equivalent volume. For example, employing a strip having a width of Mt" and a thickness of .005", the power handling capabilities are increased over a round wire having an equivalent volume. This increase of power handling capabilities is provided by the larger cooling area for each of the strips. If the number of conducting strips placed upon the base 30 cause the spacing of the strip to limit the potential difference that can exist between the strips, it is possible to ridge the ceramic base between the strips as is now the practice in a conventional stern press to increase the potential difference required for breakdown.

The embodiments of our frequency coupling means and novel stem press configuration arenot limited to their application in traveling wave electron discharge devices. It must be understood that the stem press arrangement may be employed in any electron discharge device presently employing the pin type stem press and that the radio frequency coupling means of this invention may be adapted to couple energy into or out of electron discharge devices incorporating resonant cavities therein, such as klystron and magnetron electron discharge devices, as well as the type of microwave electron discharge device herein described.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.

We claim:

1. A traveling Wave electron discharge device comprising an envelope, means at one end of said envelope for producing a beam of electrons for flow along a given path within said envelope, a propagating structure disposed along said path for propagation of radio frequency wave energy for interaction with the electrons of said beam, radio frequency terminal means disposed externally of said envelope and an impedance matching means coupling energy from said terminal means to said propagating structure including a ceramic member disposed crosswise a portion of said one end of said envelope, a line of conductive material disposed adjacent one surface of said member extending between said terminal means and said propagating structure, conductive means disposed adjacent the other surface of said member to present a parallel planar conducting surface with respect to said line of conductive material to function in conjunction therewith as a waveguide for said wave energy, and means sealing said one surface and said line of conductive material to said envelope.

2. A device according to claim l, wherein said conductive material is carried by said ceramic member.

3. A device according to claim l, wherein said ceramic member carries said line of conductive material and said conductive means on the opposite surfaces thereof.

4. A device according to claim l, wherein said conductive means includes an end plate disposed crosswise said one end of said envelope adjacent said ceramic member and in supporting relationship to said propagating structure, said end plate providing said planar conducting surface.

5. A traveling wave electron discharge device cornprising an envelope, means at one end of said envelope for producing a beam of electrons for flow along a given path within said envelope, a propagating structure disposed along said path for propagation of radio frequency wave energy for interaction with the electrons of said beam, input and output radio frequency terminal means disposed externally of said envelope, a rst impedance matching means disposed adjacent said one end of said envelope for coupling energy from said input terminal -to said propagating structure, and a second impedance matching means disposed adjacent the end of said envelope opposite said one end of said envelope for coupling energy from said propagating structure to said output terminal, each of said matching means including a ceramic member disposed crosswise said envelope, a line of conductive material disposed adjacent one surface of said ceramic member extending between said terminal means and said propagating structure, conductive means disposed adjacent the other surface of said ceramic member to present a parallel planar conducting surface with respect to said line of conductive material to function in conjunction therewith as a waveguide for said wave energy, and means sealing said one surface and said line of conductive material to said envelope.

6. A traveling wave electron discharge device comprising a ceramic envelope, means at one end of said envelope for producing a lbeam of electrons for ow along a given path within said envelope, a helical propagating structure of relatively high characteristic impedance disposed along said path for propagation of radio frequency wave energy for interaction with the electrons of said beam, input and output radio frequency transmission line terminal means of relatively low characteristic impedance disposed externally of said envelope, a first annular end plate disposed crosswise said one end of said envelope and in supporting relationship to the end of said propagating structure adjacent said one end of said envelope, a second annular end plate disposed crosswise the end of said envelope opposite said one end of said envelope and in supporting relationship to the end of said propagating structure adjacent said opposite end of said envelope, input impedance matching means disposed adjacent said first end plate for coupling energy in a substantially reflectionless manner from said input terminal means to said propagating structure, an output impedance matching means disposed adjacent said second end plate for coupling energy in a substantially retlectionless manner from said propagating structure to said output terminal means, each of said matching means including an annular ceramic wafer disposed crosswise said envelope and positioned to have one surface 'thereof contiguous said end plate,av conductive line carried by the other surface of said wafer, said end plate presenting a parallel planar conducting surface with respect tosaid conductive line to function in conjunction therewith as a waveguide for said radio fre quency wave energy, means coupling said conductive line and said end plate together externally of saidl envelope at a given point to establish a voltage null, meansv within saidenvelope disposed adjacent a high voltage portion of' said Vconductive line in coupled relation with saidI propa gating structure, means coupling said conductive line to said` terminal means at a point intermediate said voltage null and said high voltage portion to provide an impedance. match between said low impedance terminal means and said high impedance propagating structure, and means sealing said` one surface and said conductive line to said envelope.

7. A traveling wave electron discharge device comprising an envelope having a tubular end portion, means disposed in said end portion for producing a beam of electrons for ow along a given path within said envelope, a propagating structure disposed along said path for propagation of radio frequency energy for interaction with the electrons of said beam, input and outputradioY frequency terminal means disposed externally of said envelope, a rst impedance matching means disposed adjacent the end of said propagating structure closest said end portion for coupling energy from said'input terminalthereto, a second impedance matching means disposed adjacent the opposite end of said structure and coupling energy therefrom to said output terminal, each of said matching means including an annular ceramic wafer disposed crosswise said envelope, a line of conductive material disposed adjacent one surface of 'said wafer extend ing between said terminal means and said propagating structure, conductive means disposed adjacent the other surface of said wafer to presenta parallel planar conducting surface with respect to said line of conductive material to function in conjunction therewith as a waveguide for said wave energy, and means sealingv said one surface and said line of conductive material to said envelope, and potential conducting means associated with said beam producing means including a ceramic disc clisposed crosswise of said end portion,. a plurality of conductive lines disposed on thesurface of said disc facing said end portion, said conductive. lines extending from points onsaid disc external of said end portion to points thereon internal of said end portion, and means sealing; said disc surface including said conductive lines to said end portion.

8i. In an electron discharge device having a ceramic:V

envelope including an end portionl and a pluralityl of elec=- trodes disposed in said end portion toproduce an electron beam-potential conducting meansto couple direct current potential to said electrodes for electron beam production comprising a ceramic disc disposed'crosswisesaid end portion,l aV plurality ofdiscrete conductive lines disposed onV the' surface of said disc facing said end portion,y said conductive'linesl extending from pointson said disc external of said end portion to points thereon' internaly of said end portion for coupling direct current potential tol respective ones of said electrodes and electrical insulating means hermetically sealing said disc surface including said conductive lines to said end portion.

9; Inan electron discharge device, an envelope having a ceramic tubular portion, a ceramic wafer disposedcrosswise of said tubular portion and extending to the exterior thereof, aV discrete conductor carried on the` surface of said wafer, and electrical insulating means hermetically sealing the ysaidsurface of said wafer and said conductor carried thereon' to said tubular portion, said conductor having a'A width substantially less than the transverse dimension of said wafer and extending from a point on` said wafer external of saidy tubular portion to a` point thereoninternal of4 said tubular portion, said tubular portion being` divided in,V two segments by said ceramic wafer,V said wafer carrying thereon a first conductor on one surface thereof and a second conductor on the opposite surface thereof, said conductors being disposed: in an overlying parallel relationship to constitute a formfofparallel waveguide,` and said sealing means seals said one of said surfaces-.and said rst conductor to one of said-segments and said opposite surface and said second conductor to the other ofsaid segments.

References Cited in the ile of this patent UNITEDv STATES PATENTS 2,516,944 Barnett Aug. 1:, 1950 2,578,434 Lindenblad Dec. 11, 1951 2,629,066v Eitel et al. Feb. 17, 1953 2,654,842 Engelmann Oct; 6', 1953 2,740,067 Sorg Mar. 27, 1956 2,794,144 White May 28, 1957 OTHER REFERENCES Article by Grieg and Engelmann, entitled, Microstrip, a New Transmission Technique for theKilomegacycle- Range, Proc. of the IRE,.December 1952, pages 1644-1650.

Article by Kostriza, entitled, Microstrip Components, Proc. ofthe. IRE, December 1952, pages 1658-1663. 

